Historically, computers communicated over dedicated communication lines or through a specific connection such as a modem connection from one computer to another. Computers have also been connected in networks that allow communication among a number of computers. Typically, human installers set up such a network in a static configuration. To change the arrangement of computers in the network, a network administrator can rearrange the cables connecting the computers, such as by rearranging the connections of network cables that plug in to a common connection box (e.g., switch, hub, or router) for that network. The network administrator can measure the usage of the network (e.g., with a monitoring device) and physically rearrange the connections in the network to a new static configuration to relieve an area of high usage or congestion. Also, when adding a new computer to the network, the network administrator can measure the usage of the network avoid an area of high usage or congestion.
In a modem network, such as the Internet based on the TCP (Transmission Control Protocol) and the IP (the Internet Protocol), a computer can establish a connection (e.g., TCP/IP connection) to another computer in the network for a period of time, and then establish another connection to an additional computer in the network for a period of time. Such connections are typically for specific purposes for transient periods of time.
Such a connection can form a pathway from one computer to another over a network (e.g., the Internet). The pathway may be based on virtual connections, as well as on the physical connections between computers. In a network like the Internet, a virtual connection between computers may be viewed as one data communications connection or pathway based on one or more underlying physical connections between the computers. For example, one client computer can make a virtual connection to a server computer by referencing an HTTP (Hypertext Transfer Protocol) hyperlink in a web page to the server. The client and server computers can be located in the same building. Alternatively, the two computers may be located in different cities. In this case, the physical connections between the two computers may pass through many intermediate computers (e.g., many nodes or hops on the Internet) while the virtual connection is viewed as one pathway (e.g., between a web site served by the server and the client computer). A pathway can change based on the activities of the client and server computers. For example, a user of web browser on a client can change the pathways to different servers by using the browser to link to different web sites.